为什么它给我一个错误 Argument must not be null？

如何解决为什么它给我一个错误 Argument must not be null？

请解释为什么它给我一个错误参数不能为空？也许这是因为照片应该显示在片段中而不是活动中。你能解释一下吗，我真的想不通。我认为问题出在这行代码 userImage = itemView 中。 findViewById(R.id.RoundedLayoutUsers);但究竟有什么问题...

public class UserAdapter extends RecyclerView.Adapter<UserAdapter.UserViewHolder> {
private List<UserModel> list;
private Context mActivity;
private DatabaseReference rootReference = FirebaseDatabase.getInstance().getReference();
private String currentUserID = FirebaseAuth.getInstance().getCurrentUser().getUid();

public UserAdapter(Context mActivity,List<UserModel> list) {
    this.list = list;
    this.mActivity = mActivity;

}

@NonNull
@Override
public UserViewHolder onCreateViewHolder(@NonNull ViewGroup parent,int viewType) {
    return new UserViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_user,parent,false));
}

@Override
public void onBindViewHolder(@NonNull UserViewHolder holder,int position) {
    UserModel user = list.get(position);
    //    Picasso.get().load(user.urlImage).into(holder.userImage);
    Glide.with(mActivity)
            .load(user.urlImage)
            .circleCrop()
            .into(holder.userImage);

}

@Override
public int getItemCount() {
    return list.size();
}

class UserViewHolder extends RecyclerView.ViewHolder{

    RoundedImageView userImage;

    TextView loginName;
    RatingBar ratingBar;

    public UserViewHolder(@NonNull View itemView) {
        super(itemView);
        userImage = itemView.findViewById(R.id.RoundedLayoutUsers);

    }
}
}

这是完整的错误代码

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.chatden,PID: 9146
java.lang.NullPointerException: Argument must not be null
    at com.bumptech.glide.util.Preconditions.checkNotNull(Preconditions.java:29)
    at com.bumptech.glide.util.Preconditions.checkNotNull(Preconditions.java:23)
    at com.bumptech.glide.RequestBuilder.into(RequestBuilder.java:669)
    at com.example.chatden.adapter.UserAdapter.onBindViewHolder(UserAdapter.java:60)
    at com.example.chatden.adapter.UserAdapter.onBindViewHolder(UserAdapter.java:32)
    at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7065)
    at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7107)
    at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6012)
    at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6279)
    at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6118)
    at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6114)
    at androidx.recyclerview.widget.LayoutState.next(LayoutState.java:98)
    at androidx.recyclerview.widget.StaggeredGridLayoutManager.fill(StaggeredGridLayoutManager.java:1607)
    at androidx.recyclerview.widget.StaggeredGridLayoutManager.onLayoutChildren(StaggeredGridLayoutManager.java:683)
    at androidx.recyclerview.widget.StaggeredGridLayoutManager.onLayoutChildren(StaggeredGridLayoutManager.java:605)
    at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4134)
    at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3851)
    at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4404)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1080)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at androidx.viewpager.widget.ViewPager.onLayout(ViewPager.java:1775)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1080)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
    at com.android.internal.policy.PhoneWindow$DecorView.onLayout(PhoneWindow.java:2706)
    at android.view.View.layout(View.java:16659)
    at android.view.ViewGroup.layout(ViewGroup.java:5452)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2216)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1976)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1124)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6072)

我想知道如果你运行毕加索然后写 Target must not be null.

解决方法

很可能 user.urlImage 为空。调试 UserModel user = list.get(position); 行并检查用户对象。